Photochromic naphthopyran compounds

ABSTRACT

Described are novel reversible photochromic naphthopyran compounds, examples of which are compounds substituted at the 3 position of the pyran ring with (i) an aryl substituent and (ii) a phenyl substituent having a 5- or 6-member heterocyclic ring fused at the number 3 and 4 carbon atoms of the phenyl substituent. Also described are organic host materials that contain or that are coated with such compounds. Articles such as ophthalmic lenses or other plastic transparencies that incorporate the novel naphthopyran compounds or combinations thereof with complementary photochromic compounds, e.g., spiro(indoline) type compounds, are also described.

DESCRIPTION OF THE INVENTION

The present invention relates to certain novel naphthopyran compounds.More particularly, this invention relates to novel photochromicnaphthopyran compounds and to compositions and articles containing suchnovel naphthopyran compounds. When exposed to light radiation involvingultraviolet rays, such as the ultraviolet radiation in sunlight or thelight of a mercury lamp, many photochromic compounds exhibit areversible change in color. When the ultraviolet radiation isdiscontinued, such a photochromic compound will return to its originalcolor or colorless state.

Various classes of photochromic compounds have been synthesized andsuggested for use in applications in which a sunlight-induced reversiblecolor change or darkening is desired. U.S. Pat. No. 3,567,605 (Becker)describes a series of pyran derivatives, including certain benzopyransand naphthopyrans. These compounds are described as derivatives ofchromene and are reported to undergo a color change, e.g., fromcolorless to yellow-orange, on irradiation by ultraviolet light attemperatures below about -30° C. Irradiation of the compounds withvisible light or upon raising the temperature to above about 0° C. isreported to reverse the coloration to a colorless state.

The present invention relates to novel naphthopyran compounds whosecolored forms have been found to have an unexpectedly higher absorptionmaxima than corresponding compounds having no substituents or differentsubstituents at the same ring position. These compounds are substitutedat the 3 position of the pyran ring with (i) an aryl substituent and(ii) a phenyl substituent having a 5- or 6-member heterocyclic ringfused at the number 3 and 4 carbon atoms of the phenyl substituent.

DETAILED DESCRIPTION OF THE INVENTION

In recent years, photochromic plastic materials, particularly plasticmaterials for optical applications, have been the subject ofconsiderable attention. In particular, photochromic ophthalmic plasticlenses have been investigated because of the weight advantage theyoffer, vis-a-vis, glass lenses. Moreover, photochromic transparenciesfor vehicles, such as cars and airplanes, have been of interest becauseof the potential safety features that such transparencies offer.

Photochromic compounds useful in optical applications, such asconventional ophthalmic lenses, are those which possess (a) a highquantum efficiency for coloring in the near ultraviolet, (b) a lowquantum yield for bleaching with white light, and (c) a relatively fastthermal fade at ambient temperature but not so rapid a thermal fade ratethat the combination of white light bleaching and thermal fade preventcoloring by the ultraviolet component of strong sunlight. In addition,the aforesaid properties are desirably retained in conventional rigidsynthetic plastic materials customarily used for ophthalmic and planolenses when such materials have applied to or incorporated therein suchphotochromic compounds.

Compounds, such as 3,3-diphenyl-3H-naphtho[2,1-b]pyran, change color onexposure to the near ultraviolet; but, at room temperature and above,this compound bleaches too rapidly for use in an ophthalmic lens.Substitution of either or both of the phenyl rings at the meta or parapositions result in an even more rapid bleach rate, and therefore aneven lower color intensity. The compound,2,2-diphenyl-2H-naphtho[1,2-b]pyran, also colors on exposure to nearultraviolet light at room temperature but does not bleach in areasonable period of time. Substitution of either or both of the phenylrings at the meta or para positions have little effect on the rate ofbleaching of these compounds.

In accordance with the present invention, it has now been discoveredthat certain novel naphthopyran compounds having a high quantumefficiency for coloring in the near ultraviolet and an acceptable rateof fade may be prepared. These compounds may be described asnaphthopyrans substituted at tile 3 position of the pyran ring with (i)an aryl substituent and (ii) a phenyl substituent having a 5- or6-member heterocyclic ring fused at the number 3 and 4 carbon atoms ofthe phenyl substituent and may be represented by the following graphicformula: ##STR1##

In graphic formula I, R₁ and R₂ may each be C₁ -C₁₀ alkyl, C₅ -C₇cycloalkyl, e.g., cyclopentyl, cyclohexyl, and cycloheptyl, halogen,R(R')N--, or the group, --O--L, wherein R and R' are each hydrogen or C₁-C₃ alkyl, L is a C₁ -C12 alkyl, e.g., methyl, ethyl, propyl, butyl,pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl,phenyl(C₁ -C₃)alkyl, e.g., benzyl, phenethyl, phenylpropyl, mono-, di-and tri(C₁ -C₃) alkylphenyl, e.g., tolyl, xylyl, mesityl, and cumenyl,C₁ -C₅ alkylcarbonyl, and halo(C₁ -C4)alkylcarbonyl, which includesmono-, di-, or tri-halo substituents, C₁ -C₄ monoalkylaminocarbonyl,acetonyl, pyridyl, substituted or unsubstituted arylcarbonyl, said arylgroup being phenyl or naphthyl, said aryl substituents being C₁ -C₄alkyl, C₁ -C₄ alkoxy, e.g., methoxy, ethoxy, propoxy, and butoxy,halogen, C₅ -C₇ cycloalkyl, or C₁ -C₄ alkyl substituted C₅ -C₇cycloalkyl, said halogen (or halo) groups described above being chloro,fluoro, or bromo, and a and b are each the integers 0, 1 or 2 providedthat the sum of a and b is not more than 2.

Preferably, R₁ and R₂ are each R(R')N--, or the group, --O--L, wherein Rand R' are each hydrogen or C₁ -C₂ alkyl, L is C₁ -C₄ alkyl, C₁ -C₂aLkylphenyl, phenyl (C₁ -C2)alkyl, C₁ -C₂ alkylcarbonyl, halo(C₁-C₂)alkylcarbonyl, or C₁ -C₂ monoalkylaminocarbonyl, said halo groupbeing chloro or fluoro, and a and b are each the integer 0 or 1.

B may be the substituted or unsubstituted aryl group, naphthyl orphenyl, said aryl substituents being C₁ -C₅ alkyl, halo (C₁ -C₅ )alkyl,hydroxy, C₁ -C₅ alkoxy, C₁ -C₄ alkoxy(C₁ -C4)alkyl, halogen, orR(R')N--, wherein R and R' are each hydrogen or C₁ -C₃ alkyl, saidhalogen (or halo) groups being fluorine, chlorine, or bromine.Preferably, B is represented by the following graphic formula II:##STR2##

In graphic formula II, R₆ is hydrogen, C₁ -C₄ alkyl, C₁ -C₄ alkoxy,fluoro, or chloro and each R₇ is a C₁ -C₄ alkyl, C₁ -C₄ alkoxy, hydroxy,chloro, or fluoro and d is an integer from 0 to 2.

B' may be represented by one of the following graphic formulae III orIV: ##STR3##

In graphic formula III and IV, X is oxygen or nitrogen and Y is carbonor oxygen, provided that when X is nitrogen, Y is carbon; R₄ and R₅ areeach hydrogen or C₁ -C₅ alkyl; each R₃ is a C₁ -C₅ alkyl, C₁ -C₅ alkoxy,hydroxy, or halogen, said halogen substituent being chloro, fluoro, orbromo, and c is an integer from 0 to 3, e.g., 0, 1, 2, or 3. Preferably,B' is represented by graphic formula III, wherein X is oxygen; Y iscarbon or oxygen; R₄ and R₅ are each hydrogen or C₁ -C₄ alkyl; each R₃is a C₁ -C₄ alkyl, C₁ -C₄ alkoxy, hydroxy, or fluoro; and c is theinteger 0, 1, or 2.

In graphic formula III, when X is oxygen and Y is carbon and c is zero,the group is a 2,3-dihydrobenzofuran-5-yl; when X is oxygen and Y isoxygen and c is zero, the group is 1,3-benzo-dioxole-5-yl; and when X isnitrogen and Y is carbon and c is zero, the group is indoline-5-yl. Ingraphic formula IV, when X is oxygen and Y is carbon, the unsubstitutedgroup is a chroman-6-yl; when X is oxygen and Y is oxygen, theunsubstituted group is a 1,4-benzodioxan-6-yl; and when X is nitrogenand Y is carbon, the unsubstituted group is1,2,3,4-tetrahydroquinoline-6-yl. For brevity, these groups will bereferred to herein as fused heterocyclic-phenyl groups.

Compounds represented by graphic formula I are prepared byFriedel-Crafts methods using an appropriately substituted orunsubstituted benzoyl chloride of graphic formula V with a commerciallyavailable fused heterocyclic-benzene compound to produce B' structuresof graphic formula III or IV. See the publication Friedel-Crafts andRelated Reactions, George A. Olah, Interscience Publishers, 1964, Vol.3, Chapter XXXI (Aromatic Ketone Synthesis), and "RegioselectiveFriedel-Crafts Acylation of 1,2,3,4-Tetrahydroquinoline and RelatedNitrogen Heterocycles: Effect on NH Protective Groups and Ring Size" byIshihara, Yugi et al, J. Chem. Soc., Perkin Trans. 1, pages 3401 to3406, 1992. If a fused heterocyclic-benzene compound containing anoxygen is not commercially available, it may be prepared from anappropriately substituted phenol as described in Organic Reactions, Vol.II, pages 26 and 27.

In reaction A shown below, the compounds represented by graphic formulaeV and III are dissolved in a solvent, such as carbon disulfide ormethylene chloride, in the presence of a Lewis acid, such as aluminumchloride, to form the corresponding heterocyclic fused benzophenonerepresented by graphic formula VII. ##STR4##

In reaction B shown below, the heterocyclic fused benzophenonerepresented by graphic formula VII is reacted with sodium acetylide in asuitable solvent, such as dry tetrahydrofuran, to form the correspondingpropargyl alcohol represented by graphic formula VIII. ##STR5##

In reaction C shown below, the propargyl alcohol represented by graphicformula VIII is coupled with the appropriately substituted 2-naphthol,represented by graphic formula IX, under acidic conditions to form thenaphthopyrans of graphic formula X, which are compounds represented bygraphic formula I. ##STR6##

By substituting the fused heterocyclic-phenyl group of graphic 5 formulaIV for that of graphic formula III in reaction A, compounds similar tothose represented by graphic formula X except for a 6-memberheterocyclic ring fused at the number 3 and 4 carbon atoms of the3-phenyl substituent may be prepared.

Compounds represented by graphic formula I may be used in thoseapplications in which organic photochromic substances may be employed,such as optical lenses, e.g., ophthalmic and plano lenses, face shields,goggles, visors, camera lenses, windows, automotive windshields,aircraft and automotive transparencies, e.g., T-roofs, sidelights, andbacklights, plastic films and sheets, textiles and coatings, e.g.,coating compositions such as paints, and verification marks on securitydocuments, e.g., documents such as banknotes, passports and drivers'licenses for which authentication or verification of authenticity may bedesired. Naphthopyrans represented by graphic formula I exhibit colorchanges from colorless to colors ranging from yellow to orange.

Examples of contemplated naphthopyrans within the scope of the inventionare the following:

(1) 3-(2,3-dihydrobenzofuran-5-yl)-3-phenyl-3H-naphtho-[2,1-b]pyran;

(2)3-(2,3-dihydrobenzofuran-5-yl)-3-(2-fluorophenyl)-3H-naphtho[2,1-b]pyran;

(3)3-(2,3-dihydrobenzofuran-5-yl)-3-(2-methoxyphenyl)-3H-naphtho[2,1-b]pyran;

(4)5-acetoxy-3-(2,3-dihydrobenzofuran-5-yl)-3-(2-fluorophenyl)-3H-naphtho[2,1-b]pyran;

(5)8-methoxy-3-(2,3-dihydrobenzofuran-5-yl)-3-(2-fluorophenyl)-3H-naphtho[2,1-b]pyran;

(6)3-(4-methoxyphenyl)-3-(2,4,7-trimethyl-2,3-dihydrobenzofuran-5-yl)-3H-naphtho[2,1-b]pyran;

(7)3-(2-methyldihydrobenzofuran-5-yl)-3-(2-fluoro-phenyl)-3H-naphtho[2,1-b]pyran;

(8) 3-(1,4-benzodioxan-6-yl)-3-(2-fluorophenyl)-3H-naphtho[2,1-b]pyran;

(9) 3-(1,3-benzodioxole-5-yl)-3-phenyl-3H-naphtho-[2,1-b]pyran;

(10) 3-(indoline-5-yl)-3-phenyl-3H-naphtho[2,1-b]pyran; and

(11)3-(1,2,3,4-tetrahydroqulnoline-6-yl)-3-phenyl-3H-naphtho[2,1-b]pyran.

Commercially available photoreactive inorganic glass lenses containingsilver halide particles darken to a neutral gray or brown color insunlight. In order to duplicate this color change in a plastic lensusing the organic photochromic naphthopyrans of graphic formula I, it iscontemplated that such naphthopyrans be used in combination with otherappropriate complementary organic photochromic materials so thattogether they produce the desired gray or brown color shade when theplastic lens containing such photochromic materials is exposed toultraviolet light. For example, a compound which colors to yellow may beblended with a compound that colors to an appropriate purple to producea brown shade. Similarly, a compound which is orange in its coloredstate will produce a shade of gray when used in conjunction with anappropriate blue coloring compound.

Particularly contemplated classes of complementary organic photochromiccompounds that may be used include: the purple/blue spiro(indoline)benzoxazines described in U.S. Pat. No. 4,816,584; spiro(indoline)pyridobenzoxazine photochromic compounds described in U.S. Pat. No.4,637,698; spiro(indoline) naphthoxazines described in U.S. Pat. Nos.3,562,172, 3,578,602, 4,215,010 and 4,342,668; and benzopyrans andnaphthopyrans having a nitrogen-containing substituent in the 2-positionof the pyran ring, as described in U.S. Pat. No. 4,818,096. All of theaforedescribed oxazine- and pyran-type organic photochromic compoundsare reported to exhibit a color change of from colorless to purple/blueon exposure to ultraviolet light. The disclosures of said U.S. Patentsare incorporated herein by reference.

Other contemplated complementary organic photochromic compounds that arereported to exhibit a color change of from colorless to yellow/orangewhen exposed to UV light that may be used in combination to augment theyellow/orange color of the naphthopyran compounds of the presentinvention include: benzopyrans and naphthopyrans having a spiroadamantane group in the 2-position of the pyran ring, as described inU.S. Pat. No. 4,826,977; and naphthopyran compounds described in U.S.Pat. No. 5,066,818.

The naphthopyran compounds of the present invention may be used inadmixture with or in conjunction with the aforedescribed complementaryor augmenting organic photochromic compounds in counts and in a ratiosuch that an organic host material to which the mixture of compounds isapplied or in which they are incorporated exhibits a substantiallyneutral color when activated with unfiltered sunlight, i.e., as near aneutral gray or brown color as possible given the colors of theactivated photochromic compounds. The relative amounts of thephotochromic compounds used will vary and depend in part upon therelative intensities of the color of the activated species of suchcompounds.

For example, the naphthopyran compounds of the present invention may becombined with one or more of the aforedescribed purple/blue oxazine-and/or pyran-type organic photochromic compounds in amounts and in aratio such that an organic host material to which the mixture ofcompounds is applied or in which they are incorporated exhibits anear-brown color. Generally, the weight ratio of the aforedescribedoxazine- and pyran-type compound(s) to the naphthopyran compound(s) ofthe present invention will vary from about 1:3 to about 3:1, e.g.,between about 1:2 or 0.75:1 and about 2:1.

A near neutral gray color exhibits a spectrum that has relatively equalabsorption in the visible range between 400 and 700 nanometers, e.g.,between 440 and 660 nanometers. A near neutral brown color exhibits aspectrum in which the absorption in the 400-550 nanometer range ismoderately larger than in the 550-700 nanometer range. An alternativeway of describing color is in terms of its chromaticity coordinates,which describe the qualities of a color in addition to its luminancefactor, i.e., its chromaticity. In the CIE system, the chromaticitycoordinates are obtained by taking the ratios of the tristimulus valuesto their sum, e.g., x=X/X+Y+Z and y=Y/X+Y+Z. Color as described in theCIE system can be plotted on a chromaticity diagram, usually a plot ofthe chromaticity coordinates x and y. See pages 47-52 of Principles ofColor Technology, by F. W. Billmeyer, Jr. and Max Saltzman, SecondEdition, John Wiley and Sons, N.Y. (1981).

The amount of photochromic substance or composition-containing sameapplied to or incorporated into a host material is not critical providedthat a sufficient amount is used to produce a photochromic effectdiscernible to the naked eye. Generally such amount can be described asa photochromic amount. The particular amount used depends often upon theintensity of color desired upon irradiation thereof and upon tile methodused to incorporate or apply the photochromic substances. Typically, themore compound applied or incorporated, the greater is the colorintensity.

Generally, the amount of each photochromic substance incorporated intoor applied to the host material may range from about 0.01 or 0.05 toabout 10 to 20 percent by weight. More typically, the amount ofphotochromic substance(s) incorporated into or applied to the hostmaterial will range from about 0.01 to about weight percent, moreparticularly, from about 0.01 to about 1 2 weight percent, e.g., fromabout 0.1 or 0.5 to about 1 weight percent, based on the weight of thehost material. Expressed differently, the total amount of photochromicsubstance incorporated into or applied to an optical host material mayrange from about 0.15 to about 0.35 milligrams per square centimeter ofsurface to which the photochromic substance(s) is incorporated orapplied.

Photochromic compounds of the present invention, mixtures of suchcompounds with other photochromic compounds, or compositions containingsame (hereinafter "photochromic substances") may be applied to orincorporated into a host material by various methods described in theart. Such methods include dissolving or dispersing the substance withinthe host material, e.g., imbibition of the photochromic substance intothe host material by immersion of the host material in a hot solution ofthe photochromic substance or by thermal transfer; providing thephotochromic substance as a separate layer between adjacent layers ofthe host material, e.g., as a part of a polymer film; and applying thephotochromic substance as part of a coating placed on the surface of thehost material. The term "imbibition" or "imbibe" is intended to mean andinclude permeation of the photochromic substance alone into the hostmaterial, solvent assisted transfer absorption of the photochromicsubstance into a porous polymer, vapor phase transfer, and other suchtransfer mechanisms. See U.S. Pat. No. 5,066,818 column 14, line 41 tocolumn 15, line 25 for examples of the above methods.

The polymer host material will usually be transparent, but may betranslucent or even opaque. The polymer product need only be transparentto that portion of the electromagnetic spectrum, which activates thephotochromic substance, i.e., that wavelength of ultraviolet (UV) lightthat produces the open form of the substance and that portion of thevisible spectrum that includes the absorption maximum wavelength of thesubstance in its UV activated form, i.e., the open form. Further, theresin color should not be such that it masks the color of the activatedform of the photochromic substance, i.e., so the change in color isreadily apparent to the observer. Preferably, the host material articleis a solid transparent or optically clear material.

Examples of host materials which may be used with the photochromicsubstances or compositions described herein include: polymers, i.e.,homopolymers and copolymers, of polyol(allyl carbonate) monomers, e.g.,diethylene glycol bis(allyl carbonate), polymers, i.e., homopolymers andcopolymers, of polyfunctional acrylate monomers, polyacrylates, whichare polymers of esters of acrylic acid or methacrylic acid, such asmethyl acrylate and methyl methacrylate, cellulose acetate, cellulosetriacetate, cellulose acetate propionate, cellulose acetate butyrate,poly(vinyl acetate), poly(vinyl alcohol), poly(vinyl chloride),poly(vinylidene chloride), polyurethanes, polycarbonates, poly(ethyleneterephthalate), polystyrene, copoly(styrene-methyl methacrylate)copoly(styrene-acrylonitrile), polyvinylbutyral and polymers, i.e.,homopolymers and copolymers, of diallylidene pentaerythritol,particularly copolymers with polyol (allyl carbonate) monomers, e.g.,diethylene glycol bis(allyl carbonate), and acrylate monomers.

Transparent copolymers and blends of the transparent polymers are alsosuitable as host materials. Preferably, the host material is anoptically clear polymerized organic material prepared from apolycarbonate resin, such as the carbonate-linked resin derived frombisphenol A and phosgene, i.e., poly(4,4'-dioxy-diphenol-2,2-propane),which is sold under the trademark, LEXAN; a poly(methyl methacrylate),such as the material sold under the trademark, PLEXIGLAS; polymerizatesof a polyol(allyl carbonate), especially diethylene glycol bis(allylcarbonate), which monomer is sold under the trademark, CR-39, andpolymerizates of copolymers of a polyol (allyl carbonate), e.g.,diethylene glycol bis(allyl carbonate), with other copolymerizablemonomeric materials, such as copolymers with vinyl acetate, e.g.,copolymers of from 80-90 percent diethylene glycol bis(allyl carbonate)and 10-20 percent vinyl acetate, particularly 80-85 percent of thebis(allyl carbonate) and 15-20 percent vinyl acetate, and copolymerswith a polyurethane having terminal diacrylate functionality, asdescribed in U.S. Pat. No. 4,360,653, cellulose acetate, cellulosepropionate, cellulose butyrate, cellulose acetate butyrate, polystyreneand copolymers of styrene with methyl methacrylate, vinyl acetate andacrylonitrile.

Polyol (allyl carbonate) monomers which may be polymerized to form atransparent host material are the allyl carbonates of linear or branchedaliphatic or aromatic liquid polyols, e.g., aliphatic glycol bis(allylcarbonate) compounds, or alkylidene bisphenol bis(allyl carbonate)compounds. These monomers can be described as unsaturated polycarbonatesof polyols, e.g, glycols. The monomers can be prepared by procedureswell known in the art, e.g., U.S. Pat. Nos. 2,370,567 and 2,403,113.

Compatible (chemically and color-wise) tints, i.e., dyes, may be appliedto the host material to achieve a more aesthetic result, for medicalreasons, or for reasons of fashion. The particular dye selected willvary and depend on the aforesaid need and result to be achieved. In oneembodiment, the dye may be selected to complement the color resultingfrom the activated photochromic substances, e.g., to achieve a moreneutral color or absorb a particular wavelength of incident light. Inanother embodiment, the dye may be selected to provide a desired hue tothe host matrix when the photochromic substance is in an inactivatedstate.

Typically, tinting is accomplished by immersion of the host material ina heated aqueous dispersion of the selected dye. The degree of tint iscontrolled by the temperature of the dye bath and the length of time thehost material is allowed to remain in the bath. Generally, the dye bathis at temperatures of less than 100° C., e.g., from 70° C. to 90° C.,such as 80° C., and the host material remains in the bath for less thanfive (5) minutes, e.g., between about 0.5 and 3 minutes, e.g., about 2minutes. The degree of tint is such that the resulting article exhibitsfrom about 70 to 85 percent, e.g., 80-82 percent, light transmission.

Adjuvant materials may also be incorporated into the host material withthe photochromic substances prior to, simultaneously with or subsequentto application or incorporation of the photochromic substances in thehost material. For example, ultraviolet light absorbers may be admixedwith photochromic substances before their application to the hostmaterial or such absorbers may be superposed, e.g., superimposed, as alayer between the photochromic substance and the incident light.Further, stabilizers may be admixed with the photochromic substancesprior to their application to the host material to improve the lightfatigue resistance of the photochromic substances. Stabilizers, such ashindered amine light stabilizers and singlet oxygen quenchers, e.g., anickel ion complex with an organic ligand, are contemplated. They may beused alone or in combination. Such stabilizers are described in U.S.Pat. No. 4,720,356. Finally, appropriate protective coating(s) may beapplied to the surface of the host material. These may be abrasionresistant coatings and/or coatings that serve as oxygen barriers. Suchcoatings are known in the art.

The present invention is more particularly described in the followingexamples which are intended as illustrative only, since numerousmodifications and variations therein will be apparent to those skilledin the art.

EXAMPLE 1 Step 1

2,3-dihydrobenzofuran (9.25 grams, 0.077 moles) was added to a reactionflask containing 100 milliliters of methylene chloride and 10.8 grams(0.077 moles) of benzoyl chloride. Aluminum chloride (12.32 grams, 0.092moles) was added slowly and the resulting mixture was stirred for 2hours under a nitrogen atmosphere. The reaction mixture was added to a 5percent aqueous hydrochloric acid solution and stirred until colorless.The organic layer was separated and the aqueous layer was back extractedwith 100 milliliters of methylene chloride. The organic portions werecombined and added to a 10 percent aqueous sodium hydroxide solutioncontaining 1 milliliter of triethylamine to remove any unreactedstarting material. The mixture was stirred and the organic layer wasseparated and dried over magnesium sulfate. The residual methylenechloride was removed under vacuum. The resulting pale yellow oil wasinduced to crystallize by dissolving it in hexane and then cooling thesolution in a dry ice/acetone bath. 7.8 grams of the crystallineproduct, 5-benzoyl-2,3-dihydrobenzofuran, was collected by vacuumfiltration.

Step 2

5-benzoyl-2,3-dihydrobenzofuran (7.8 grams, 0.035 mole) from Step 1 wasadded to a reaction flask containing 300 milliliters of tetrahydrofuransaturated with acetylene. 10.0 grams of a 18 weight percent suspensionof sodium acetylide in xylene/mineral oil (0.035 moles of sodiumacetylide) was added slowly to tile stirred solution. After 16 hours atroom temperature and under a nitrogen atmosphere, the reaction mixturewas dissolved in 5 percent aqueous hydrochloric acid solution. Theresulting mixture was extracted with three 100 milliliter portions ofmethylene chloride. The organic extracts were combined and dried overmagnesium sulfate. The solvent, methylene chloride, was removed undervacuum to yield 7.0 grams of the product containing1-(2,3-dihydrobenzofuran-5-yl)-1-phenyl-2-propyn-1-ol which was notpurified further but used directly in the next step.

Step 3

The product (7.0 grams) from Step 2 was added to a reaction flaskcontaining 300 milliliters of benzene and 4.0 grams of2-hydroxynaphthalene. A catalytic amount of dodecylbenzenesulfonic acid(3 drops) was added. The mixture was heated to 40° C. and stirred for 1hour under a nitrogen atmosphere. Afterwards, the reaction mixture wasdissolved in distilled water and washed with about 300 milliliters of 10percent aqueous sodium hydroxide. The organic layer was separated, driedover magnesium sulfate and the remaining benzene was removed undervacuum. The resulting residue was induced to crystallize by dissolvingit in a hexane/ether mixture and cooling tile mixture in a dryice/acetone bath. The resulting crystals were collected by vacuumfiltration, dissolved in a 9:1 mixture of hexane:ethyl acetate, stirredfor one half hour, and collected by vacuum filtration. The crystallineproduct, about 3.0 grams, melted at 128-131° C. and was 97.7% pure asdetermined by liquid chromatographlc analysis. A nuclear magneticresonance (NMR) spectrum showed the solid crystalline product to have astructure consistent with3-(2,3-dihydrobenzofuran-5-yl)-3-phenyl-3H-naphtho-[2,1-b]pyran.

EXAMPLE 2

The procedure of Step 1 of Example 1 was utilized except for thefollowing: 2-fluorobenzoyl chloride (13.2 grams, 0.083 mole) was usedinstead of benzoyl chloride; the mixture was stirred for one hour; andthe combined organic fraction was back extracted with distilled water.19.5 grams of product containing5-(2-fluoro-benzoyl-2,3-dihydrobenzofuran was recovered.

The procedure of Step 2 of Example 1 was utilized except that5-(2-fluorobenzoyl)-2,3-dihydrobenzofuran (8 grams, 0.033 moles) wasused as the reactant; the reaction mixture was stirred 20 hours; 10%aqueous hydrochloric acid was used to dissolve the reaction mixture; andthe combined organic fraction was washed with two portions of water,about 300 milliliters each. The yield of product containing1-(2,3-dihydrobenzofuran-5-yl)-1-(2-fluorophenyl)-2-propyn-1-ol was 7.0grams.

The procedure of Step 3 of Example 1 was utilized except that1-(2,3-dihydrobenzofuran-5-yl )-1-(2-fluorophenyl)-2-propyn-1-ol (7.0grams), toluene (300 milliliters), and a catalytic amount ofp-toluenesulfonic acid (3 drops) were used; and the reaction mixture washeated to 45° C. After the organic layer was separated, the aqueouslayer was washed once with about 100 milliliters of methylene chlorideand the organic fractions were combined. The combined organic extractswere dried over magnesium sulfate and reduced under vacuum to yield 7.0grams of oil.

The oil was purified using a silica gel column and a 1:4 mixture ofethyl acetate:hexane as the eluant. The photochromic fractions werecollected, combined and the remaining eluant was removed under vacuum.The crystals were isolated as described in Step 3 of Example 1. Thecrystalline product, 3.0 grams, melted at 110°-113° C. and was 99.8%pure as determined by liquid chromatographic analysis. A nuclearmagnetic resonance (NMR) spectrum showed the solid crystalline productto have a structure consistent with 3-(2,3-dihydrobenzofuran-5-yl)-3-(2-fluorophenyl )-3H-naphtho[2,1-b ]-pyran.

EXAMPLE 3

The procedure of Step 1 of Example 1 was followed except that 2-anisoylchloride (14.2 grams, 0,083 moles) was used as the reactant instead ofbenzoyl chloride and the reaction mixture was stirred for one hour. 16.7grams of the crystalline product,5-(2-methoxybenzoyl)-2,3-dihydrobenzofuran, was recovered and used inthe next step. The procedure of Step 2 of Example 1 was followed exceptthat the combined organic fraction was washed with distilled water. Theyield of product containing1-(2,3-dihydrobenzo-furan-5-yl)-1-(2-methoxyphenyl)-2-propyn-1-ol was16.7 grams.

The procedure of Step 3 of Example 1 was utilized except that theproduct containing1-(2,3-dihydrobenzofuran-5-yl)-1-(2-methoxyphenyl)-2-propyn-1-ol and acatalytic amount of p-toluenesulfonic acid were used; the reactionmixture was heated to 35° C.; and the oil purification procedure ofExample 2 was used. The resulting crystalline product, 3.7 grams, meltedat 142°-144° C. and was 99.5% pure as determined by liquidchromatographic analysis. A nuclear magnetic resonance (NMR) spectrumshowed the solid crystalline product to have a structure consistent with3-(2,3-dihydrobenzofuran-5-yl)-3-(2-methoxyphenyl)-3H-naphtho-[2,1-b]pyran.

EXAMPLE 4

The procedure of Step 1 of Example 1 was utilized except that2-fluorobenzoyl chloride (13.2 grams, 0.083 mole) was used as thereactant instead of benzoyl chloride, the mixture was stirred for onehour, and the combined organic fraction was back extracted withdistilled water. 19.5 grams of product containing5-(2-fluorobenzoyl)-2,3-dihydrobenzofuran was recovered. The procedureof Step 2 of Example 1 was followed except that5-(2-fluorobenzoyl)-2,3-dihydrobenzofuran (5 grams, 0.02 mole) was usedand the combined organic fraction was washed with distilled water. Theyield of product, a yellow oil containing1-(2,3-dihydrobenzofuran-5-yl)-l-(2-fluorophenyl)-2-propyn-1-ol, was 4.3grams.

The procedure of Step 3 of Example 1 was utilized except that1-(2,3-dihydrobenzofuran-5-yl)-l-(2-fluorophenyl)-2-propyn-1-ol (4.3grams) from Step 2, 3-acetoxy-2-naphthol (3.3 grams, 0.016 mole), and acatalytic amount of p-toluenesulfonic acid were used; the reactionmixture was heated to 45° C.; and the oil purification procedure ofExample 2 was used. The resulting crystalline product, 4.6 grams, meltedat 156°-157° C. and was 99.0% pure as determined by liquidchromatographic analysis. A nuclear magnetic resonance (NMR) spectrumshowed the solid crystalline product to have a structure consistent with5-acetoxy-3-(2,3-dihydrobenzofuran-5-yl)-3-(2-fluoro-phenyl)-3H-naphtho[2,1-b]-pyran.

EXAMPLE 5

The procedure of Step 1 of Example 1 was followed except that2-fluorobenzoyl chloride (13.2 grams, 0,083 mole) was used as thereactant instead of benzoyl chloride and the mixture was stirred for onehour. 16.0 grams of the product, 5-(2-fluorobenzoyl)-2,3-dihydrobenzofuran, was recovered. The procedure of Step 2 of Example 1was followed using 5-(2-fluorobenzoyl)-2,3-dihydrobenzofuran (12.5grams, 0,051 mole) from Step 1. The yield of product, containing1-(2,3-dihydrobenzofuran-5-yl)-l-(2-fluoro-phenyl)-2-propyn-1-ol, was11.0 grams.

The procedure of Step 3 of Example 1 was utilized except that1-(2,3-dihydrobenzofuran-5-yl)-l-(2-fluorophenyl)-2-propyn-1-ol (5.0grams) from Step 2, 6-methoxy-2-hydroxynaphthalene, and a catalyticamount of p-toluenesulfonic acid were used; the reaction mixture washeated to 35° C. and stirred for 1.5 hours; and the oil purificationprocedure of Example 2 was used. The resulting crystalline product, 4.3grams, melted at 164°-167° C. and was 95.0% pure as determined by liquidchromatographic analysis. A nuclear magnetic resonance (NMR) spectrumshowed the solid crystalline product to have a structure consistent with8-methoxy-3-(2,3-dihydrobenzofuran-5-yl)-3-(2-fluorophenyl)-BH-naphtho[2,1-b]pyran.

EXAMPLE 6 Step 1

2,5-dimethylphenol (30.0 grams, 0.25 mole) was added to a reaction flaskcontaining 300 milliliters of ethyl alcohol and 17.0 grams (0.3 mole) ofpotassium hydroxide. Allyl bromide (36.3 grams, 0.3 mole) was addedslowly to the stirred solution over a period of 15 minutes. The reactionmixture was refluxed in a nitrogen atmosphere for four hours. The excesssolvent was removed under vacuum and the residual solid was dissolved in200 milliliters of 5% aqueous sodium hydroxide and extracted with threeportions of methylene chloride, about 100 milliliters each. The organicextracts were combined, dried over magnesium sulfate, and reduced undervacuum to yield 33.3 grams of a yellow oil containing the desiredproduct, 2,5-dimethylphenyl allyl ether.

Step 2

2,5-dimethylphenyl allyl ether (33.3 grams, 0.21 mole) from Step 1 wasadded to a reaction flask equipped with a water condenser and heated to195° C. with stirring under a nitrogen atmosphere. After 2 hours, thetemperature was reduced to 140° C. and several drops ofdodecylbenzenesulfonic acid were added. The reaction mixture was slowlyheated to 195° C. and held there for 3 hours. The reaction mixture wascooled and dissolved in 5% aqueous sodium hydroxide. The resultingmixture was extracted with three 100 milliliter portions of methylenechloride. The organic extracts were combined, dried over magnesiumsulfate and reduced under vacuum. The resulting product was distilled ata head temperature of 80° C. under a reduced pressure of 6 mm Hg toyield 11.0 grams of a clear colorless oil. A nuclear magnetic spectrum(NMR) showed the product to have a structure consistent with2,3-dihydro-2,4,7-trimethylbenzofuran.

Step 3

2,3-dihydro-2,4,7-trimethylbenzofuran (5.0 grams, 0.031 mole) from Step2 was added to a reaction flask containing 300 milliliters of methylenechloride and 5.3 grams (0.031 mole) of p-anisoyl chloride. Aluminumchloride (5.0 grams, 0.037 mole) was added slowly to the stirredsolution. After 1.5 hours the reaction mixture was dissolved in 20%aqueous hydrochloric acid and stirred for 10 minutes. The organic layerwas separated and the aqueous layer was washed once with 100 millilitersof methylene chloride. The organic extracts were combined, washed withabout 200 milliliters of distilled water, separated, and dried overmagnesium sulfate. The solvent, methylene chloride, was removed undervacuum yield 7.0 grams of product containing the desired ketone,5-(4-methoxybenzoyl)-2,4,7-trimethyl-dihydrobenzofuran.

Step 4

5-(4-methoxybenzoyl)-2,4,7-trimethyldihydrobenzofuran (7.0 grams, 0.024mole) from Step 3 was added to a reaction flask containing 300milliliters of tetrahydrofuran saturated with acetylene. 8.1 grams of a18 weight percent solution of sodium acetylide in xylene/light mineraloil (0.028 mole of sodium acetylide) was added to the stirred solution.After 72 hours the reaction mixture was dissolved in 10% aqueoushydrochloric acid and extracted with three portions of methylenechloride, about 100 milliliters each. The organic extracts were combinedand dried over magnesium sulfate. The methylene chloride was removedunder vacuum. The product containing1-(2,3-dihydro-2,4,7-trimethyl-benzofuran)-5-yl-1-(4-methoxyphenyl)-2-propyn-1-olwas used directly in the next step.

Step 5

1-(2,3-dihydro-2,4,7-trimethylbenzofuran)-5-yl-1-(4-methoxyphenyl)-2-propyn-1-ol(5.0 grams) from Step 4 was added to a reaction flask containing 300milliliters of benzene and 2.3 grams (0.016 mole) of2-hydroxynaphthalene. A catalytic amount of p-toluenesulfonic acid wasadded to the stirred solution and the mixture was heated to 35° C. undera nitrogen atmosphere. After 1.5 hours, the reaction mixture wasdissolved in 20% aqueous sodium hydroxide and extracted with threeportions of methylene chloride, about 100 milliliters each. The organicextracts were combined and dried over magnesium sulfate. The methylenechloride was removed under vacuum. The product was purified using asilica gel column and a 1:4 mixture of ethyl acetate:hexane as theeluant. The photochromic fractions were combined and the remainingeluant was removed under vacuum. The residual oil was crystallized fromhexane to yield 200 mg. of the desired photochromic compound. Thecrystalline product melted at 162°-164° C. and was 98.8% pure asdetermined by liquid chromatographlc analysis. A nuclear magneticresonance (NMR) spectrum showed the solid crystalline product to have astructure consistent with3-(4-methoxyphenyl)-3-(2,4,7-tri-methyldihydrobenzofuran-5-yl)-3H-naphtho[2,1-b]pyran.

EXAMPLE 7

2-methyldihydrobenzofuran was prepared by the method described inExample 6, Steps 1 and 2, using phenol instead of 2,5-dimethyl phenol inStep 1. For further information respecting the synthesis, see OrganicReactions, Volume II, pages 26 and 27. The procedures of Steps 1, 2, and3 of Example 1 were followed using 2-methyldihydrobenzofuran in place of2,3-dihydrobenzofuran in Step 1. The resulting product was 98.6% pure asdetermined by liquid chromatographic analysis. A nuclear magneticresonance (NMR) spectrum showed the product to have a structureconsistent with3-(2-methyldihydrobenzofuran-5-yl)-3-(2-fluorophenyl)-3H-naphtho[2,1-b]pyran.

EXAMPLE 8

The procedure of Step 1 of Example 1 was utilized except that2-fluorobenzoyl chloride (5.0 grams, 0.032 mole) was used instead ofbenzoyl chloride; 1,4-benzodioxan (4.4 grams, 0.032 mole) was usedinstead of 2,3-dihydrobenzofuran; and the reaction mixture was stirredfor 1 hour. 8.0 grams of the white crystalline product,5-(2-fluorobenzoyl)-1,4-benzodioxan, was recovered. The procedure ofStep 2 of Example 1 was followed except that5-(2-fluoro-benzoyl)-1,4-benzodioxan (8.0 grams, 0.031 mole) was usedand the reaction mixture was stirred for 20 hours. The yield of productcontaining 1-(1,4-benzodioxan-6-yl)-l-(2-fluorobenzoyl)-2-propyn-1-olwas 7.0 grams.

The procedure of Step 3 of Example 1 was utilized except that productcontaining 1-(1,4-benzodioxan-6-yl )-1-(2-fluoro-benzoyl)-2-propyn-1-ol(7.0 grams) from Step 2, 2-naphthol (3.6 grams), and a catalytic amountof p-toluenesulfouic acid were used; the mixture was stirred for 2hours; and the oil purification procedure of Example 2 was used. Theresulting crystalline product, about 0.5 gram, melted at 143°-147° C.and was 97.3% pure as determined by liquid chromatographic analysis. Anuclear magnetic resonance (NMR) spectrum showed the solid crystallineproduct to have a structure consistent with3-(1,4-benzodioxan-6-yl)-3-(2-fluorophenyl)-3H-naphtho[2,1-b]pyran.

EXAMPLE 9 Step 1

Piperonal (10.0 grams, 0.067 moles) was added to a reaction flaskcontaining 100 milliliters of tetrahydrofuran. Phenyl magnesium bromide(0.08 moles) was added slowly and the resulting mixture was heated to66° C. and stirred for 1 hour under a nitrogen atmosphere. The reactionmixture was added to a 5 percent aqueous hydrochloric acid and icesolution. The organic layer was separated and the aqueous layer waswashed with three 100 milliliter portions of methylene chloride. Theorganic portions were combined and dried over magnesium sulfate. Theresidual methylene chloride was removed under vacuum. About 15.0 gramsof a white/yellow oil product was recovered. A nuclear magneticresonance (NMR) spectrum showed the product to be consistent withalpha-phenyl-1,3-benzodioxole-5-methanol.

Step 2

Alpha-phenyl-1,3-benzodioxole-5-methanol (10.0 grams, 0.044 mole) fromStep 1 was dissolved in a reaction flask containing 300 milliliters ofmethylene chloride and pyridinium dichromate (25.0 grams, 0.066 mole)was added. After 16 hours at room temperature and under a nitrogenatmosphere, the reaction mixture was diluted with diethyl ether andvacuum filtered to remove the solids. The liquid portion was subjectedto evaporation to yield 8.3 grams of a slightly viscous off white oil. Anuclear magnetic resonance (NMR) spectrum showed the product to have astructure consistent with 5-benzoyl-1,3-benzodioxole.

Step 3

The procedure of Step 2 of Example 1 was followed except that5-benzoyl-l,3-benzodioxole (8.3 grams) was used as a reactant instead of5-(benzoyl)-2,3-dihydrobenzofuran and after the reaction mixture wasstirred for 22 hours at room temperature, the pH was reduced to about2.0. The yield of product containing1-(1,3-benzodioxole-5-yl)-1-phenyl-2-propyn-1-ol was 9.0 grams.

Step 4

1-(1,3-benzodioxole-5-yl)-l-phenyl-2-propyn-1-ol (3.5 grams, 0,014 mole)from Step 3 and 2-naphthol (2.0 grams, 0,014 mole) were added to areaction flask containing 300 milliliters of toluene. A catalytic amountof p-toluenesulfonic acid was slowly added and the reaction mixture wasstirred for 2 hours at room temperature under a nitrogen atmosphere.Afterwards, the reaction mixture was added to 200 milliliters of 20%aqueous sodium hydroxide and washed. The organic layer was separated anddried over magnesium sulfate. The solids were filtered and the resultingoil was purified on a silica gel column using chloroform as the eluant.The resulting orange oil was induced to crystallize by dissolving it ina hexane/ether mixture and cooling the mixture in a dry ice/acetonebath. The resulting crystals were collected by vacuum filtration. Thecrystalline product, about 4.1 grams, melted at 168°-170° C. and was99.8% pure as determined by liquid chromatographic analysis. A nuclearmagnetic resonance (NMR) spectrum showed the solid crystalline productto have a structure consistent with3(1,3-benzodioxole-5-yl)-3-phenyl-3H-naphtho[2,1-b]pyran.

COMPARATIVE EXAMPLE 1

1,1-diphenyl-2-propyn-1-ol (20.8 grams, 0.1 mole) was added to areaction flask containing 200 milliliters of benzene and 15 grams of2-naphthol. The reaction mixture was warmed to 55° C. and after all ofthe 2-naphthol was dissolved, 0.25 grams of p-toluenesulfonic acid wasadded to the stirred reaction mixture. The mixture changed from lighttan to dark black, became exothermic, and the temperature rose to 70° C.After a few minutes, the reaction mixture lightened and began to cool.After 30 minutes, the reaction mixture was poured into 100 millilitersof 10 percent aqueous sodium hydroxide and shaken. The organic phase waswashed once with 10 percent aqueous sodium hydroxide and then washedwith water. The solvent, benzene, was removed on a rotary evaporator.The resulting light tan solid residue was slurried with 100 millilitersof hexane and filtered. The filtered solid was washed again with 100milliliters of hexane and dried to provide 18.4 grams of the product,3,3-diphenyl-3H-naphtho[2,1-b]pyran. The solid product had a meltingpoint of 156°-158° C. and was 98 percent pure as determined by liquidchromatographic analysis.

COMPARATIVE EXAMPLE 2

Anisole (10.8 grams, 0.1 mole) and benzoyl chloride (14 grams, 0.1 mole)were dissolved in 200 milliliters of hexane and stirred at roomtemperature. Anhydrous aluminum chloride, 15 grams, was added slowly tothe reaction mixture over a period of 15 minutes. The reaction mixturewas stirred an additional 15 minutes. The hexane was decanted and theresulting viscous residue was carefully hydrolyzed with 200 millilitersof a mixture of ice and dilute hydrochloric acid. The organic fractionwas taken up in dichloromethane and the resulting solution was washedwith water. Dichloromethane was removed on a rotary evaporator leavingan oil product that solidified on standing. The solidified product wasbroken-up, washed with two 50 milliliter portions of pentane, and dried,yielding 4-methoxybenzophenone.

10 grams of this 4-methoxybenzophenone was converted to the propargylalcohol by the procedure described in Step 2 of Example 1. NMR analysisof the resulting product showed it to be a mixture of compounds havingstructures consistent with 1-phenyl-l(4-methoxyphenyl)-2-propyn-1-ol andthe starting ketone, 4-methoxybenzophenone, in a ratio of 3:1.

The crude propargyl alcohol was added to a reaction flask containing aslurry of 5 grams of 2-naphthol, 40 grams of anhydrous acid alumina and200 milliliters of toluene. The resulting reaction mixture was heated toreflux for 30 minutes, cooled, and filtered. The alumina was washed twotimes with 100 milliliter portions of hexane. Time toluene and hexanefractions were combined and the organic solvents were removed on arotary evaporator. The resulting product was an orange oil that wasinduced to crystallize by dissolving it in a mixture of hexane anddiethyl ether and then cooling the solution in a dry ice/acetone bath.The product crystals were washed with diethyl ether and dried to yield1.4 grams of a product having a melting point of 149°-150° C. A nuclearmagnetic resonance (NMR) spectrum showed the solid product to have astructure consistent with3-phenyl-3(4-methoxyphenyl)-3H-naphtho-[2,1-b]pyran.

COMPARATIVE EXAMPLE 3

The procedures of Steps 1 and 2 of Example 1 were followed except thatanisole was used instead of 2,3-dihydrobenzofuran and 2-fluorobenzoylchloride was used instead of benzoyl chloride in Step 1. The resultingproduct contained1-(4-methoxy-3-methyl-phenyl)-1-(2-fluorophenyl)-2-propyn-1-ol. Theprocedure of Step 3 of Example 1 was utilized except that1-(4-methoxy-3-methylphenyl)-1-(2-fluorophenyl)-2-propyn-1-ol (5.5grams, 0.02 mole) from the previous step, 2-naphthol (3.0 grams), and acatalytic amount of p-toluenesulfonic acid were used; and the reactionmixture was heated to 35° C. and stirred for several hours.

The resulting oil product was purified on a silica gel column using a1:5 mixture of ethyl acetate:hexane as the first eluant followed by a1:1 mixture of chloroform:hexane as the second eluant. The filtrate wascollected and the solvent was removed to yield 2.0 grams of a solidproduct. The solid product had a melting point of 98° C. and was 99%pure as determined by liquid chromatographic analysis. A nuclearmagnetic resonance (NMR) spectrum showed the solid product to have astructure consistent with3-(4-methoxy-3-methylphenyl)-3-(2-fluorophenyl)-3H-naphtho-[2,1-b]pyran.

EXAMPLE 10 Part A

The naphthopyran prepared in Example 9 was incorporated into an ethylcellulose resin by the following procedure. 25 milligrams of thephotochromic compound was added to 2.0 grams of a 10 weight percentethyl cellulose solution in toluene. The naphthopyran compound wasdissolved by warming and stirring on a steam bath. Approximately 2.0grams of the resultant solution was deposited on the edge of a 75 by 25millimeter (nun) glass slide. Using a draw down bar, an 8 mm layer ofphotochromic resin solution was placed evenly on the slide and permittedto dry.

Part B

Further testing was done on selected naphthopyrans that were imbibed bythermal transfer into test squares of a homopolymer of diethylene glycolbis(allyl carbonate) by the following procedure. Each naphthopyran wasdissolved into toluene solvent to form a 4 weight percent solution ofthe compound. A piece of No. 4 Whatman filter paper was saturated withthe naphthopyran solution and allowed to air dry. The dried filter paperwas placed on one side of the polymer test square, which measured 1/8inch (0.3 centimeter)×2 inch (5.1 centimeters)×2 inch (5.1 centimeters).A piece of untreated filter paper was placed on the other side of thepolymer test square and the resulting sandwich placed between two platesof flat aluminum metal plates. The entire assembly was then placed in a155° C. oven for a time sufficient to thermally transfer thenaphthopyran into the polymer test square. Residence times in the ovenwere adjusted to imbibe comparable amounts of the naphthopyran compoundsin order to yield a comparable UV absorbance at 347 nm. The imbibed testsquares were washed with acetone after removal from the oven.

Part C

Both sets of polymer test samples were tested for photochromic responserates on an optical bench. The samples were illuminated by a 150 wattXenon lamp fitted with a copper sulfate bath and a neutral densityfilter at an intensity of about one sun. A second beam of light providedby a filtered tungsten lamp arranged to pass through the sample areaexposed by the UV source was used to monitor changes in transmission ofthe sample over different wavelength ranges in the visible region of thespectrum. The intensity of the monitoring beam after passing through thesample was measured by means of an IL-1500 radiometer equipped with asilicon detector head and matching filters.

The Δ OD/Min, which represents the sensitivity of the photochromiccompound's response to UV light, was measured using photopic filters onthe silicon detector. The response of the filtered detector approximatedthe luminosity curve. The Δ OD/Min was measured over the first five (5)seconds of UV exposure, then expressed on a per minute basis. Thesaturation optical density (OD) was taken under identical conditions asthe A OD/Min, except UV exposure was continued for 20 minutes for theexamples in Table 1 and for 15 minutes for the examples in Table 2. Thelambda max reported in Tables 1 and 2 is the wavelength in the visiblespectrum at which the maximum absorption of the activated (colored) formof the photochromic compound in poly (diethylene glycol bis (allylcarbonate)) in Table 1 and in ethyl cellulose resin in Table 2 occurs.The Bleach Rate T 1/2 is the time interval in seconds for the absorbanceof the activated form of the naphthopyran in the test polymers to reachone half the highest absorbance at room temperature (72° F., 22.2° C.)after removal of the source of activating light. Results are tabulatedin Tables 1 and 2.

                                      TABLE 1                                     __________________________________________________________________________    Poly[diethylene glycol bis(allyl carbonate)] Samples                                    LAMBDA                                                                              Δ OD/Min                                                                        Δ OD @                                                                           BLEACH RATE                                            MAX   SENSITIVITY                                                                           SATURATION                                                                             T 1/2 (SEC.)                                 __________________________________________________________________________    COMPOUND                                                                      EXAMPLE                                                                       1         478 nm                                                                              0.62    0.20     33                                           2         475 nm                                                                              0.86    0.90     179                                          3         482 nm                                                                              1.02    1.76     >600                                         4         490 nm                                                                              0.31    0.66     368                                          5         488 nm                                                                              0.91    1.73     624                                          6         485 nm                                                                              0.53    0.61     363                                          7         479 nm                                                                              0.91    0.90     151                                          8         463 nm                                                                              0.83    1.00     261                                          COMPARATIVE                                                                   EXAMPLE                                                                       1         432 nm                                                                              0.87    0.36     45                                           2         468 nm                                                                              0.66    0.25     35                                           3         467 nm                                                                              0.96    0.97     191                                          a.*       476 nm                                                                              0.45    1.36     >30  min.                                    __________________________________________________________________________     *a. Purchased 2,2diphenyl-2H-naphtho[1,2b]pyran                          

                                      TABLE 2                                     __________________________________________________________________________    Ethyl Cellulose Samples                                                                 LAMBDA                                                                              Δ OD/Min                                                                        Δ OD @                                                                           BLEACH RATE                                            MAX   SENSITIVITY                                                                           SATURATION                                                                             T 1/2 (SEC.)                                 __________________________________________________________________________    COMPOUND                                                                      EXAMPLE                                                                       9         459 nm                                                                              0.66    0.31     41                                           COMPARATIVE                                                                   EXAMPLE                                                                       1         432 nm                                                                              0.87    0.31     32                                           __________________________________________________________________________

The data tabulated in Tables 1 and 2 show that all of the CompoundExamples, except Compound Examples 8 and 9, have lambda max valuescloser to 480 nm than Comparative Examples 1, 2, and 3. CompoundExamples 8 and 9 have lambda max values much higher than ComparativeExample 1 which has two phenyl groups at the 3 position of the pyranring. Comparative Example "a" has a lamda max of 476 but the bleach rateis unacceptably slow for use in an ophthalmic lens application.

Although the present invention has been described with reference to thespecific details of particular embodiments thereof, it is not intendedthat such details be regarded upon the scope of the invention exceptinsofar as to the extent that they are included in the accompanyingclaims.

I claim:
 1. A naphthopyran compound represented by the following graphicformula: ##STR7## wherein, (a) R₁ and R₂ are each C₁ -C10 alkyl, C₅ -C₇cycloalkyl, halogen, R(R')N--, or the group, --O--L, wherein R and R'are each hydrogen or C₁ -C₃ alkyl, L is C₁ -C₁₂ alkyl, phenyl(C₁-C₃)alkyl, C₁ -C₃ alkylphenyl, C₁ -C₅ alkylcarbonyl, halo(C₁-C₄)alkylcarbonyl, C₁ -C₄ monoalkylaminocarbonyl, acetonyl, pyridyl,substituted or unsubstituted arylcarbonyl, said aryl group being phenylor naphthyl, said aryl substituents being C₁ -C₄ alkyl, C₁ -C₄ alkoxy,halogen, C₅ -C₇ cycloalkyl, or C₁ -C₄ alkyl substituted C₅ -C₇cycloalkyl, said halogen (or halo) groups being chloro, fluoro, orbromo; and a and b are each the integers 0, 1, or 2, provided that thesum of a and b is not more than 2.(b) B is the substituted orunsubstituted aryl group, naphthyl or phenyl, said aryl substituentsbeing C₁ -C₅ alkyl, halo(C₁ -C₅)alkyl, hydroxy, C₁ -C₅ alkoxy, C₁ -C₄alkoxy(C₁ -C₄)alkyl, halogen, or R(R')N--, wherein R and R' are eachhydrogen or C₅ -C₇ alkyl, and said halogen (or halo) groups beingfluorine, chlorine, or bromine; and (c) B' is selected from the groupsrepresented by the following graphic formulae: ##STR8## wherein X isoxygen and Y is carbon or oxygen; R₄ and R₅ are each hydrogen or C₁ -C₅alkyl; each R₃ is a C₁ -C₅ alkyl, C₁ -C₅ alkoxy, hydroxy, or halogen,said halogen being chloro, fluoro, or bromo, and c is an integer from 0to
 3. 2. A naphthopyran of claim 1 wherein:(a) R₁ and R₂ are each C₁ -C₅alkyl, C₅ -C₆ cycloalkyl, fluorine, bromine, R(R')N--, or the group--O--L, wherein R and R' are each hydrogen or C₁ -C₂ alkyl, L is C₁ -C₄alkyl, C₁ -C₂ alkylphenyl, phenyl(C₁ -C₂)alkyl, phenylcarbonyl, C₁ -C₂alkylcarbonyl, halo(Cl-C2)alkylcarbonyl, or C₁ -C₂monoalkylaminocarbonyl, said halo group being chloro or fluoro; and aand b are the integers 0 or 1; (b) B is represented by the followinggraphic formula: ##STR9## wherein R₆ is hydrogen, C₁ -C₄ alkyl, C₁ -C₄alkoxy, fluoro, or chloro, each R₇ is a C₁ -C₄ alkyl, C₁ -C₄ alkoxy,hydroxy, chloro or fluoro, and d is an integer from 0 to 2; and (c) B'is selected from the groups represented by the following graphicformulae: ##STR10## wherein X is oxygen, Y is carbon or oxygen, R₄ andR₅ are each hydrogen or C₁ -C₄ alkyl, each R₃ is a C₁ -C₄ alkyl, C₁ -C₄alkoxy, hydroxy, or fluoro, and c is an integer from 0 to
 2. 3. Anaphthopyran compound of claim 2 wherein R₁ and R₂ are each C₁ -C₃alkyl, fluorine or the group --O--L, wherein L is acetyl, benzoyl,methyl, or methylaminocarbonyl; B is phenyl or substituted phenyl, saidphenyl substituents being fluoro, methyl, or methoxy; B' is2,3-dihydrobenzofuran-5-yl, 2-methyldthydrobenzofuran-5-yl,indoline-5-yl, chroman-6-yl, or 1,3-benzodioxole-5-yl and d is theinteger 0 or
 1. 4. A naphthopyran compound selected from the groupconsisting of:(a) 3-(2,3-dihydrobenzofuran-5-yl)-3-phenyl-3H-naphtho-[2,1-b]pyran; (b) 3-(2,3-dihydrobenzofuran-5-yl)-3-(2-fluorophenyl)-3H-naphtho[2,1-b]pyran; (c)3-(2,3-dihydrobenzofuran-5-yl)-3-(2-methoxyphenyl)-3H-naphtho[2,1-b]pyran; (d)3-(2-methyldihydrobenzofuran-5-yl)-3-(2-fluoro-phenyl)-3H-naphtho[2,1-b]pyran;(e)8-methoxy-3-(2,3-dihydrobenzofuran-5-yl)-3-(2-fluorophenyl)-3H-naphtho[2,1-b]pyran;(f) 3-(4-methoxyphenyl)-3-(2,4,7-trimethyl-2,3-dihydrobenzofuran-5-yl)-3H-naphtho[2,1-b]pyran; and (g) 3-(1,3-benzodioxole-5-yl)-3-phenyl-3H-naphtho-(2,1-b)pyran.
 5. A photochromic article comprisingan organic host material and a photochromic amount of a naphthopyrancompound represented by the following graphic formula: ##STR11##wherein, (a) R₁ and R₂ are each C₁ -C₁₀ alkyl, C₅ -C₇ cycloalkyl,halogen, R(R')N--, or the group, --O--L, wherein R and R' are eachhydrogen or C₁ -C₃ alkyl, L is C₁ -C₁₂ alkyl, phenyl(C₁ -C₃)alkyl, C₁-C₃ alkylphenyl, C₁ -C₅ alkylcarbonyl, halo(C₁ -C4)alkylcarbonyl, C₁ -C₄monoalkylaminocarbonyl, acetonyl, pyridyl, substituted or unsubstitutedarylcarbonyl, said aryl group being phenyl or naphthyl, said arylsubstituents being C₁ -C₄ alkyl, C₁ -C₄ alkoxy, halogen, C₅ -C₇cycloalkyl, or C₁ -C₄ alkyl substituted C₅ -C₇ cycloalkyl, said halogen(or halo) groups being chloro, fluoro, or bromo; and a and b are eachthe integers 0, 1, or 2, provided that the sum of a and b is not morethan 2;(b) B is the substituted or unsubstituted aryl group, naphthyl orphenyl, said aryl substituents being C₁ -C₅ alkyl, halo(C₁ -C₅)alkyl,hydroxy, C₁ -C₅ alkoxy, C₁ -C₄ alkoxy(C₁ -C₄)alkyl, halogen, orR(R')N--, wherein R and R' are each hydrogen or C₁ -C₃ alkyl, and saidhalogen (or halo) groups being fluorine, chlorine, or bromine; and (c)B' is selected from the groups represented by the following graphicformulae: ##STR12## wherein X is oxygen and Y is carbon or oxygen; R₄and R₅ are each hydrogen or C₁ -C₅ alkyl; each R₃ is a C₁ -C₅ alkyl, C₁-C₅ alkoxy, hydroxy, or halogen, said halogen being chloro, fluoro, orbromo, and c is an integer from 0 to
 3. 6. The photochromic article ofclaim 5 wherein the organic host material is selected from the groupconsisting of polyacrylates, cellulose acetate, cellulose triacetate,cellulose acetate propionate, cellulose acetate butyrate, poly(vinylacetate), poly(vinyl alcohol), poly(vinyl chloride), poly(vinylidenechloride), polycarbonate, polyurethane, poly(ethylene terephthalate),polystyrene, copoly(styrene-methylmethacrylate),copoly(styrene-acrylonitrile, polyvinylbutyral and polymers of membersof the group consisting of polyol(allyl carbonate) monomers,polyfunctional acrylate monomers, and diallylidene pentaerythritolmonomers.
 7. The photochromic article of claim 6 wherein:(a) R₁ and R₂are each C₁ -C₅ alkyl, C₅ -C₆ cycloalkyl, fluorine, bromine, R(R' )N--,or the group --O--L, wherein R and R' are each hydrogen or C₁ -C₂ alkyl,L is C₁ -C₄ alkyl, C₁ -C₂ alkylphenyl, phenyl(C₁ -C₂)alkyl, C₁ -C₂alkylcarbonyl, halo(C₁ -C₂)alkylcarbonyl, or C₁ -C₂monoalkylaminocarbonyl, said halo group being chloro or fluoro; and aand b are the integers 0 or
 1. (b) B is represented by the followinggraphic formula: ##STR13## wherein R₆ is hydrogen, C₁ -C₄ alkyl, C₁ -C₄alkoxy, fluoro, or chloro, each R₇ is a C₁ -C₄ alkyl, C₁ -C₄ alkoxy,hydroxy, chloro, or fluoro, and d is an integer from 0 to 2; and (c) B'is selected from the groups represented by the following graphicformulae: ##STR14## wherein X is oxygen, Y is carbon or oxygen, R₄ andR₅ are each hydrogen or C₁ -C₄ alkyl, each R₃ is a C₁ -C₄ alkyl, C₁ -C₄alkoxy, hydroxy, or fluoro, and c is an integer from 0 to
 2. 8. Thephotochromic article of claim 7 wherein R₁ and R₂ are each C₁ -C₃ alkyl,fluorine or the group --O--L, wherein L is acetyl, benzoyl, methyl, ormethylaminocarbonyl; B is phenyl or substituted phenyl, said phenylsubstituents being fluoro, methyl, or methoxy; B' is2,3-dihydrobenzofuran-5-yl; 2-methyldihydrobenzofuran-5-yl,chroman-6-yl, or 1,3-benzodioxole-5-yl, and d is the integer 0 or
 1. 9.The photochromic article of claim 8 wherein the organic host material isa solid transparent homopolymer or copolymer of diethylene glycolbis(allyl carbonate), carbonate-linked resin derived from4,4'-dioxydiphenyl-2,2-propane and phosgene, poly(methylmethacrylate),polyvinylbutyral, or a polyurethane.
 10. The photochromic article ofclaim 9 wherein the photochromic compound is present in an amount offrom about 0.15 to 0.35 milligrams per square centimeter of organic hostmaterial surface to which the photochromic substance(s) is incorporatedor applied.
 11. The photochromic article of claim 10 wherein the articleis a lens.
 12. A photochromic article comprising a solid transparentpolymerized organic host material and a photochromic amount of each of(a) a first photochromic substance selected from the group consisting ofspiro(indoline) naphthoxazines, spiro(indoline) pyridobenzoxazines, andspiro(indoline) benzoxazines, and benzopyrans or naphthopyrans having anitrogen-containing substituent in the 2-position of the pyran ring, and(b) a second photochromic substance selected from naphthopyran compoundsrepresented by the following graphic formula: ##STR15## wherein, (a) R₁and R₂ are each C₁ -C₁₀ alkyl, C₅ -C₇ cycloalkyl, halogen, R(R')N--, orthe group, --O--L, wherein R and R' are each hydrogen or C₁ -C₃ alkyl, Lis C₁ -C₁₂ alkyl, phenyl(C₁ -C₃)alkyl, C₁ -C₃ alkylphenyl, C₁ -C₅alkylcarbonyl, halo(C₁ -C₄)alkylcarbonyl, C₁ -C₄ monoalkylaminocarbonyl,acetonyl, pyridyl, substituted or unsubstituted arylcarbonyl, said arylgroup being phenyl or naphthyl, said aryl substituents being C₁ -C₄alkyl, C₁ -C₄ alkoxy, halogen, C₅ -C₇ cycloalkyl, or C₁ -C₄ alkylsubstituted C₅ -C₇ cycloalkyl, said halogen (or halo) groups beingchloro, fluoro, or bromo; and a and b are each the integers 0, 1, or 2,provided that the sum of a and b is not more than 2;(b) B is thesubstituted or unsubstituted aryl group, naphthyl or phenyl, said arylsubstituents being C₁ -C₅ alkyl, halo(C₁ -C₅)alkyl, hydroxy, C₁ -C₅alkoxy, C₁ -C₄ alkoxy(C₁ -C₄)alkyl, halogen, or R(R')N--, wherein R andR' are each hydrogen or C₁ -C₃ alkyl, and said halogen (or halo) groupsbeing fluorine, chlorine, or bromine; and (c) B' is selected from thegroups represented by the following graphic formulae: ##STR16## whereinX is oxygen and Y is carbon or oxygen provided; R₄ and R₅ are eachhydrogen or C₁ -C₅ alkyl; each R₃ is a C₁ -C₅ alkyl, C₁ -C₅ alkoxy,hydroxy or halogen, said halogen being chloro, fluoro, or bromo, and cis an integer from 0 to
 3. 13. The photochromic article of claim 12wherein the organic host material is selected from the group consistingof polyacrylates, cellulose acetate, cellulose triacetate, celluloseacetate propionate, cellulose acetate butyrate, poly(vinyl acetate),poly(vinyl alcohol), poly(vinyl chloride), poly(vinylidene chloride),polycarbonate, polyurethane, poly(ethylene terephthalate), polystyrene,copoly(styrene-methylmethacrylate), copoly(styrene-acrylonitrile,polyvinylbutyral and polymers of members of the group consisting ofpolyol(allyl carbonate) monomers, polyfunctional acrylate monomers, anddiallylidene pentaerythritol monomers.
 14. The photochromic article ofclaim 13 wherein:(a) R₁ and R₂ are each C₁ -C₅ alkyl, C₅ -C₆ cycloalkyl,fluorine, bromine, R(R')N--, or the group --O--L, wherein R and R' areeach hydrogen or C₁ -C₂ alkyl, L is C₁ -C₄ alkyl, C₁ -C₂ alkylphenyl,phenyl(C₁ -C₂)alkyl, C₁ -C₂ alkylcarbonyl, halo(C₁ -C₂)alkylcarbonyl, orC₁ -C₂ monoalkylaminocarbonyl, said halo group being chloro or fluoro;and a and b are the integers 0 or 1; (b) B is represented by thefollowing graphic formula: ##STR17## wherein R₆ is hydrogen, C₁ -C₄alkyl, C₁ -C₄ alkoxy, fluoro, or chloro, each R₇ is a C₁ -C₄ alkyl, C₁-C₄ alkoxy, hydroxy, chloro, or fluoro, and d is an integer from 0 to 2;and (c) B' is selected from the groups represented by the followinggraphic formulae: ##STR18## wherein X is oxygen, Y is carbon or oxygen,R₄ and R₅ are each hydrogen or C₁ -C₄ alkyl, each R₃ is C₁ -C₄ alkyl, C₁-C₄ alkoxy, hydroxy, or fluoro, and c is an integer from 0 to
 2. 15. Thephotochromic article of claim 14 wherein R₁ and R₂ are each C₁ -C₃alkyl, fluorine or the group --O--L, wherein L is acetyl, benzoyl,methyl, or methylaminocarbonyl; B is phenyl or substituted phenyl, saidphenyl substituents being fluoro, methyl, or methoxy; B' is2,3-dihydrobenzofuran-5-yl; 2-methyldihydrobenzofuran-5-yl,chroman-6-yl, or 1,3-benzodioxole-5-yl, and d is the integer 0 or
 1. 16.The photochromic article of claim 15 wherein the organic host materialis a solid transparent homopolymer or copolymer of diethylene glycolbis(allyl carbonate), carbonate-linked resin derived from4,4'-dioxydiphenyl-2,2-propane and phosgene, poly(methylmethacrylate),polyvinylbutyral, or a polyurethane.
 17. The photochromic article ofclaim 16 wherein the photochromic compound is present in an amount offrom about 0.15 to 0.35 milligrams per square centimeter of organic hostmaterial surface to which the photochromic substance(s) is incorporatedor applied.
 18. The photochromic article of claim 17 wherein the weightratios of the first photochromic substance to the naphthopyran compoundis from about 1:3 to about 3:1.
 19. The photochromic article of claim 18wherein the article is an ophthalmic lens.